1. Field of the Invention
The present invention relates to an optical data reading device, such as a bar code reader, and especially to an improvement in a light source for illuminating an object, such as a bar-code.
2. Description of the Related Art
In a conventional opitcal data reading device, illuminating light is radiated onto an object, such as a bar code, so that an image of the bar code is formed on the light receiving surface of a CCD (charge coupled device) by the light reflected from the bar code. A signal outputted from the CCD, i.e., a signal corresponding to the image of the bar code, is inputted into an image signal processing circuit so that the signal is subjected to a predetermined process, and thus, the bar code is decoded. The light source for illuminating the bar code is an illuminating device, such as a halogen lamp, a fluorescent lamp or the like, and is separately provided from the optical data reading device.
The illuminating device, however, can be restricted when the light source unit of the illuminating device is too bulky to be located near the optical data reading device. Accordingly, there are problems in that the arrangement of the illuminating device is inconvenient and that illuminating the bar code with a uniform and proper brightness is difficult. Further, the illuminating device is expensive and may need a special power source, which makes the construction of the optical data reading device complex.